There's also the issue of why should the World Champion continue to automatically get to the final... I suppose it's a bit different with Chess, in that if you become World Champion in any given year it's likely you'll stay strong enough to be in the top 2 the following year, but that's not always the case.
Imagine if Tiger Woods won the Masters one year, then every year after that he got to enter the final round tied for the lead. It's no wonder there's only been 16 undisputed world champions since 1886!
Here's how the World Championship challenger should be decided:
Let's keep the same qualification methods to get to the candidates.
The candidates then play a 7-round Swiss, with white/black determined by ratings/selection method, i.e. give 4 whites to Top qualifiers. This could take place in Feb.
Following the tournament, a month later, the top four compete in a semi-final, best of 6 games. A month later this is followed by a best of 8 challenger final.
This way the challenger has proven themselves in both regular season qualification, swiss-play against top field, and two match play events. That way a worthy challenger is guaranteed.
Having a single double-round tournament 8 months before the event doesn't really give us the best outcome.
There's not nearly enough match-play in top level chess now, much like in Golf, so why not play events in that fashion in order to determine the best?